Posts like this always make me want to play with a layout engine trying to implement various features. Is there a toy layout engine made specifically for (self-) education? I couldn't find one. If there isn't, what is otherwise the easiest one to get started with?
Or contribute to Servo! Despite the huge milestone represented by Acid 2, it's still pretty early days and there is plenty of work to go around. The code's on GitHub [1], Josh Matthews did a nice talk about Fosdem that should give you a start on the architecture and how to contribute (video [2], slides [3]), and there is an irc channel (#servo on irc.mozilla.org) where you can ask questions.
WeasyPrint is a layout engine written in Python. It is not written for education nor it is a toy, but I found it easier to understand compared to other engines.
